1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to Surface Acoustic Wave (SAW) filters, and more particularly, to programmable SAW filters in which a filtering characteristic can be programmed in a desired format.
2. Description of the Related Art
SAW filters extract desired signals from input signals and output the desired signals using an SAW principle. Such SAW filters when configured as passive filters do not consume power during their operations. Thus, SAW filters are used, for example, in portable terminals in which power consumption must be reduced.
Such an SAW filter is realized by alternately forming output and ground electrodes having comb structures on a piezoelectric substrate. A filtering characteristic of the SAW filter is determined based on distances and overlapped degrees between the output and ground electrodes. Positions and structures of the output and ground electrodes formed on the piezoelectric substrate may not be adjusted. Thus, the filtering characteristic of the SAW filter is determined in advance during manufacturing of the SAW filter, and the determined filtering characteristic cannot be changed.
However, the filtering characteristic of the SAW filter may be required to be changed during the use of the SAW filter. Thus, an SAW filter whose filtering characteristic can be changed when necessary must be realized.